Photoengraving



Dec. 15, 1942. RX, 2,304,838

PHOTOENGRAVING Filed Jan. 4, 1940 0- a STHTE I STATE H INVENTOR.

ATTORNEY.

Patented Dec. 15, 1942 2,304,838 rnoroaneaavmc Walter s. Marx, Jr., ParkRidge, 11]., animalto Printing Arts Research laboratories, lnc.,Chicago, 111., a corporation oi Delaware Application January 4, 1940,Serial No. 312,348

8 Claims.

This invention relates to photo-engraving, and more particularly to amethod of forming highlight negatives for halt-ton printing plates aswell as to means for preparing drawings from which such negatives can beproduced. This application is a continuation in part or my applicationSerial No. 209,492, which resulted in Patent No. 2,191,939.

An object of this invention is to provide a simple method ofhighlighting" that is free from the more lengthy and inexpedientprevailing methods, such as laborious hand-painting or handopaquing, orwhich involve the employment of special lenses and stops that are inmany instances impractical and depend upon delicately balanced exposurerelationships, and which in any event are limited to the reproduction ofcertain types of copy only.

A further object or the invention is to provide a method of, and meansfor, greatly reducing the cost of highlight half-tone printing plates bydecreasing the production time, and substituting for the presentdiflicult manual method of highcorded, and the second exposure with thehalftone screen effectually removed and by means of light changed infrequency by a molecular change in energy levels resulting fromtheinclusion of predetermined substances in the work areas of thedrawing or subject to be photographed, as will hereinafter be disclosedin detail, the non-work or highlight areas remaining unchanged and arethus photographed in said second exposure to the extent required toefiectually cover or efface the' latent-half-tone record or highlightdots of the first exposure without affecting the half-tone pattem'in thework areas.

Th first of the above mentioned exposures is made in the presence ofvisible or ordinary lightwhilst the second exposure is made in thepresence of light rays lying outside of the visible spectrum, that is tosay, rays outside the visible spectrum at its violet end, namely,ultra-violet rays, or those rays'which lie just beyond said spectrum atits red end, namely, infra-red rays.

Th order of the two exposures may, of course, be reversed, as will beunderstood.

A further object of this invention is to improve the accuracy ofreproduction of highlight drawings and similar illustrative matter'bythe employment of a marking device, such as a pencil.

To this end the present invention also relates to a pencil, the markingmaterial of which includes a substance which will absorb infra-red lightor ultra-violet light in such a way that when the markings made by hepencil are photographed by means or such light and with visible or whitelight in the manner already outlined in connection with the method ofthis invention above, a highlight halt-tone printing plate may be madephoto-automatically from a drawing or subject prepared with such pencil.

The word "pencil is used herein for convenience of description and istherefore to be considered as including in meaning all types of markingdevices, such as crayons, pastels, pencil leads, pens, quills, etc., themarkings of which may be applied in either liquid or solid phases, orboth.

A highlight half-tone printing plate" as herein used is to be understoodto mean, asit does in th art, a screened printing plate which is free ofdot pattern or other half-tone scanning in the background and/orhighlighted areas of the matter so reproduced.

Furthermore, it is to be considered for the purpose of descriptionherein that ultra-violet and infra-red energy forms are actually lightwaves, and that as such they may be measured, used, and theoreticallycalculated for conclusions demonstrable from that basis.

Other objects and advantages or the invention will be apparent from thefollowing detailed description by referring to the accompanying drawing,in which: V

Figure 1 is an enlarged section of a marking made-with the pencil ofthis invention, and

Figures 2 and 3 are structural formulae showing the chemicalconstitution of markings made with a pencil of this invention, Figure 2representing para-hydroxybenzaldehyde, and Figure 3 representinganthracene, each compound being typical in general of intra-molecularand intermolecular energy absorption materials respectively, and eachfigure shows the behavior of these materials during the herein describedwork thereon, and under the influence of light energy.

According to this invention, the following for- .mula may be used formaking up. a pencil, the

markings of which, when made alkaline, will efiectually absorbultra-violet light:

Extrude under heavy pressure at to degrees C. Dry for fifty hours. 7

After the drawing to be reproduced has been 'marking.

2 asoeass withapencilasabovemadeupitis sprayed or otherwise coated withan alkalising material. A preferred method is to spray the drawing witha volatile alkaiising compound. madeasiollows: Y

Parts by volume Isopropyl alcohol 85 Chemically pure glycerine 10Morpholine 5 a This spraying compound is preferred became the alkalinematerial volatilises 01!, leaving the markingsmadehythepencil andsupporting-surfacethereoiinamoreneutral andtly more stable condition,sincemost drawing pap oxidise more rapidly in an alkaline state.

Each microscopic particle, or group 01partltionindicatedbyllandonitsinnerlimitshytheperipheryoftheparticleniseiiectually sorben oi ultra-violet light.

Thus,ifAinFigureiisblack (asintheease of a black pencil) it will absorbboth white and intro-violet light; whereas regionf B as defined abovewill. absorb only in the ultra-violet. Therefore-ii region B is livetimes the area of regionLtheregipnABwillabsorbsixt-imesmore ultra-violetlight than white li t.

The theory upon which the present invention isbasedhingesupon justthatam'plincationof light absorption. The relative numerical. value ofabsorption quantais, of course, dependentdireetlyuponthearearatioofBtoA. Also,the spread of theumbelliierctiesolution over B, anddeterminingthesizeoil3,iseontrolledbythenatureandquantityoithe spray.

Themannerinwhichtheabovelightabsorptionprinciplecanheutilizedssameamicrphoto-automatieproduction of highlight halitone printing platesisasfollows:

The drawing or marking of which region ABisapart,isphotographedintwosteps,theiirst step comprising the normalseries of half-tone exposures through proper lens diaphragms andhalf-tone screen, and using white light in the normal manner, thusrecording upon the negativeelementahali-tonerecordoithemarking ordrawing madewiththe presentpendlzflhesecondstepbeinganauxiliaryexposurcsuperimposeduponthereeordoithefirststep,andmadebymeiinsoif ultra-violet lightonlyandwiththe half-tone screeneiiectually removed Irom the system. Thenlh-a-violetlightreflectediromall regionsaroundABwillrecordcmtinuously over allregions on the ne ative element,-thus veiling over or covering up theheretofore unexposed openings on the negativeelemmtwhichweleproiectedthereonbythe halfetone screen in the first step.The screen pattern,ordots,aretherebyeiiectuallyeliminatedinallareasonthenegative element correspondingtothennmarkedoreiieetuallyuntreated areason the surface supporting the towhite light, and. eiiectuallyab-.oonverscmtheregionanwm havelittleorho appreciable enectonthenegativeelement during theexposurebyultrawiolet 8 w il area does not eileetuallyreflectultra-violet light,

butrather absorhsitduetoenergy-transfermce whichmaybeexplainedasfollows:

Itmaybecontendedthatalllight absorptionistheresultoiinterorintramoleailarenergy absorptiomdirectlyorindirectly.Thisismore mt'rueoftheenergytransierenceinvolved for the purpose or thisinvention. Therefore, the application of both types of energyabsorptionwillbeexplained,andtheuseofany materialsalightinsuchmanner,when usediorthesamepurposeandtothesameendasthathereindisclomisconsideredaswithin .thescopeofthisinvmtion.

InFigureLregicnBiscoveredwiththeumbellifemne solution as previouslydescribed. 111s residual salt of this umbelliferone solution may be M;:;-I meturallybyeither anorthoor para quinonoid formula. Since thestructural formula for beta-methyi-mnbelliferone is, in this conmction,highly complex, the equivalent and a simpler formula will he givenwithreference to m r p hydehydeas unexample of intra molecularenergyabsorption.

Figure 2 shows parai aneutralconditionanditsconflm tioninan alkaline don, and the t change toaquinonoidstruetme. The phenoliehydrogmisioniriedoii,leavingthenegativeionnivhiiehcan'existinthetwofonns'shwnMm oneoxygenatomtoanother. Itisthatmobileehactrcnandthestruchnereslflting from its movement which absorbslight.Or what thephenolicoxygenhokistheelecmasinstate LtheenergyislowerthanwhmIngeneralthis electronieactivityismdicaflveoitheacflcnotmanylight-ahsorbing compounds of theintra-molecularmergyabsorptiai type," wheretheifreeelectronorelech'omgotromoneormoremergylevelstoanother,suchasquininesifliate,nuoreaccin,coppersultate,andnearly allrareearthsalmetc.

HSHI'QSanenmpleMintennM 'm in this case anthraccne,

andshowsthebehavioroi' such compoundedthesameabsotptiongroupmiforinstanoe,

tmnovertothedi-moleculariormaandas hereimmeismadeol.

thatenergy Someiurther mergy absorlingwhiehmaybeusedtothesameenmandwhich absorbinsitmsuchasthesaltotmtheintramolecuiar group,orsuchas anthraeeneintheintet moleculargroup,areqitionaltsd asthisinvmtimbecamethesecompmmdsareperse,-inanenergyabsorhingstate.Also,oompoundswhiehamorbenergythroughdecompositionarewithinthescopeotthismventimastallingwithinflieabove70 limitsofmolecularenergyabsorptioncharaeteristics.lnbrienanylishtormergy materialormaterials, whenmedtoachievethehereinendirrespeetiveol t nmc u eunplcmsreasraumii-withmthescopeotthepmescutinvmtion.

Grams- This mixture is heated to 180 C. and extruded at high pressureand driedin any manner well known in the art for 50 hours.

Variations of the above formula including in fra-red absorbents otherthan copper sulfate. may be used to the same end. a

Moreover, sprays or coatings of materials intended to spread-suchinfra-red absorbent beyond its otherwise normal conflner-(as has beenshown in the case of the ultra-violet absorbents)are also required inthis case. To spread copper sulfate particles for instance, water andalcohol may be used in equal parts. The spray or coating will,.oi'course, in any case contain an efl'ective quantity of a solvent in whichthe absorbent used is very highly soluble, and also a detergent capableof spreading the solution so formed, beyond its otherwise normalperiphery.

It will be understood that any suitable infrared sensitizing dye isincluded in the photo-sensitive element used for the photography ofinscriptions made by the above marking device aforedescribed and,furthermore, that infra-red light will be substituted for theultra-violet lightutilized as hereinbefore described in connection withthe employment of a marking device containing an absorbent of the latterlight.

I claim: I

1. Method of half-tone photography which comprises the steps of making adrawing from which a half-tone printing plate is to be prepared with amarking device, the marking material of which includes a pigment and asubstance capable of absorbing light lying outside of the visiblespectrum, treating the drawing, with a material adapted to render saidsubstance more eflective' to absorb said light, photographing thedrawing so prepared and treated on a light-sensitive element inaccordance with the usual halftone procedure and then superimposing onsaid light-sensitive element a second image of said drawing in thepresence of light rays lying outside of the visible spectrumcorresponding to those which the drawing has been rendered effective toabsorb. I

2. Method of half-tone photography which comprises the steps of making adrawing from which a half-tone printing plate is to be prepared with amarking device, the marking material of which includes a pigment and asubstance capable of absorbing light lying outside of the visiblespectrum, treating the drawing with a solution adapted to render saidsubstance more eflective to absorb said light and capable of amplifyingthe area of the drawing over which said absorbent action is eiiective,photographing the drawing so prepared and treated on a lightsensitiveelement in accordance with the usual Kaolin Benzojc acid 30 Phenanthrene15 Copper sulfate 20 Gum a nimn 5 Graphite 5 Pigment I 10 and five gramsof the following: 7

. Parts White beeswax I 3 Camauba w 5 half-tone vprocedure. and thensuperimposing 76 on said light-sensitive element a second image -of saiddrawing in the presence of light rays ,lying outside of the visiblespectrum corresponding to those which the drawing has been renderedeffective to absorb.

3. Method 01 halt-tone photography which comprises the steps of making adrawing from which a half-tone printing plate is to be prepared with amarking device, the marking material of which includes a pigment andasubstance capable of absorbing ultra-violet light, treating the drawingwith a material adapted to render said substance more effective toabsorb said light, photographing the drawing so prepared and treated ona light-sensitive element in accordance with the usual half-toneprocedure and then superimposing on said lightsensitive element a secondimage of said drawing in the presence only of ultra-violet light.

4. Method of half-tone photography which comprises the steps of making adrawing from which a half-tone printing plate is to be prepared with amarking device, the marking material of which includes a pigment and asubstance capable of absorbing infra-red light, treating the drawingwith a material adapted to cause said substance to diilfuse,photographing the drawing so prepared and treated on a light-sensitiveelement in accordance with the usual halftone procedure and thensuperimposing on said light-sensitive element a second image of saiddrawing in the presence only of infra-red light.

5. Method of half-tone photography which comprises the steps of makingthe drawing from which a halftone printing plate is to be pre-- paredwith a marking device, the marking material of which includes a pigmentand betamethyl-umbelliferone, applying an alkalizing material to thedrawing so prepared, photographing said drawing on a light-sensitiveelement in accordance with the usual half-tone procedure and thensuperimposing on said light-sensitive element a second image of saiddrawing in the presence only of ultra-violet light.

6. A method of half-tone photography for eliminating screen pattern inthe highlight portions of a half-tone negative, comprising incorporatingin a marking device a pigment and an absorbent of light rays lyingoutside of the visible spectrum, preparing a drawing to be photographedwith the aid of said marking device, photographing said drawing on alightsensitive element in accordance with the usual half-tone procedure,and then superposing on said element and in register'with the firstimage, a second image of said drawing in the presence only of light rayslying outside of the visible spectrum corresponding to those which the.drawing'has been rendered efiective to absorb.

7. Method of half-tone photography for eliminating screen pattern in thehighlight portions" of a half-tone negative, comprising incorporating ina solid marking device a pigment and an absorbent of light rays lyingoutside of the visible spectrum, preparing a drawing to be photographedwith the aid of said marking device, thereby producing on the drawingshaded portions constituted by a plurality of discrete separateparticles of the marking device, treating the drawing with a solvent forsaid substance whereby some of said substance included within saiddiscrete particles is dissolved and distributed over areas of thedrawing around and adjacent said discrete particles, photographing saiddrawing on a light sensitive element with twoseparateregisteringexposuregoneofsnidezpcsurmbelngeiifectedwiththeaidofascreeninaccordance with usual half-toneprocedure, the other ofsaidexposuresbeingmadewiththescreenelfectlmllyremovedandwiththeaironlyotlight rays lying outside of thevisible spectrum and corresponding to those which the drawing has beenrendered effective to absorb; the lasttioned exposure being made afterthe solventtreatment of the dralwing.

8. Method of half-tone by for eliminating screen pattern in thehighlight portions of a, half-tone negative; comprising incorporating ina solid marking device a pigment'and an absorbent of ultra-violet lightrays, preparing a drawing to he photographed with the aidoi said markingf'device, thereby producing on the drawment of the drawing I exposures.oneofsaidbeingeflectedwiththenidofnscreeninaccordancewithusinlhnlt-tone'procedure, the other of said exposures being made with the screeneffectually removed and with the aid of ultra-violet light only, thelast-mentioned exposure beingmade after the solvent treat 'wnm'za s.MARX. a.

